Large Microplastics Research Articles

Size effect of polystyrene microplastics on the accumulation of anthracene for Java medaka (Oryzias javanicus)

Pollution by microplastics in aquatic ecosystems is a worldwide problem, and the role of microplastics as vectors of pollutants has been a concern. Although small microplastics are thought to have a greater effect than large microplastics as vectors of pollutants, the impact of the size of microplastics on their ability to serve as vectors of pollutants has not been quantified. In this study, we conducted the 14-day experiment (7 days of exposure and 7 days of depuration) with polystyrene microplastics (2-μm or 10-μm diameter) and anthracene. On the last day of the exposure period, the concentration of anthracene in the muscle of Java medaka exposed to both anthracene and 2-μm polystyrene microplastics was the highest (47.4 ± 15.2 μg/g-muscle) of any group, followed by the group exposed to both anthracene and 10-μm polystyrene microplastics (23.0 ± 4.2 μg/g-muscle) and the group exposed to only anthracene (11.2 ± 2.2 μg/g-muscle). These results demonstrated that the size of microplastics was a critical determinant of their ability to serve as vectors of anthracene. The concentrations of anthracene and fine microplastics in the environment are sufficiently low that the effect of microplastics as vectors of anthracene may be observed only under experimental conditions that are unlikely to occur in the present environment. However, because pollution by plastics is expected to become more serious in the future, careful thought and proactive action will be needed to ensure that the impact of microplastics as vectors of pollutants does not become demonstrable under future environmental conditions.

Microplastic biofilm: An important microniche that may accelerate the spread of antibiotic resistance genes via natural transformation

Microplastic (MP) biofilms provide a specific microniche for microbial life and are a potential hotspot for the horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs). Nevertheless, the acquisition of ARGs in MP biofilms via natural transformation mediated by extracellular DNA (eDNA) has been rarely explored. This study demonstrated that MP biofilms promoted the natural transformation of extracellular ARGs at the single-cell and multi-species levels, compared to natural substrate (NS) biofilms and bacterioplankton. The transformation frequency on MP biofilms was up to 1000-fold compare to that on NS. The small MPs and aged MPs enhanced the ARG transformation frequencies up to 77.16-fold and 32.05-fold, respectively, compared with the large MPs and pristine MPs. The transformation frequencies on MP biofilms were significantly positively correlated with the bacterial density and extracellular polymeric substance (EPS) content (P < 0.05). Furthermore, MPs significantly increased the expression of the biofilm formation related genes (motA and pgaA) and DNA uptake related genes (pilX and comA) compared to NS and bacterioplankton. The more transformants colonized on MPs contributed to the enhanced transformation frequencies at the community-wide level. Overall, eDNA-mediated transformation in MP biofilms may be an important path of ARG spread, which was promoted by heterogeneous biofilm.

The impact of riverine particles on the vertical velocities of large microplastics

Microplastics interact with other suspended particles in aquatic systems, which may impact their environmental fate. Little is known about aggregation between suspended sediment and larger microplastics (1–5 mm), and how this impacts the vertical velocities of microplastics, although it was hypothesised these are size limited. Consumer items made of five common polymers: polypropylene (PP), high density polyethylene (HDPE), polyethylene terephthalate (PET), polyvinyl chloride (PVC) and polystyrene (PS), were fragmented by cryomilling and their vertical velocities (rising/settling) measured experimentally before and after 24-hours of aggregation with riverine particles. Microplastic size (microscopy), zeta potential and density (density gradient column) were measured, with aggregation quantified using microscopy. PP had an experimental density of 1052 kg·m−3, and sank in river water, although it is often stated as being buoyant based on literature density values. Aggregation occurred with all five polymers: 39 %–72 % of microplastics were observed to have sediment and/or organic particles adhered, depending on the polymer type. PVC had the least negative zeta potential, −8.0 ± 3.0, and showed a much higher number of adhered sediment particles than all other polymers: on average 4.55 particles, compared with <1.72 particles for other polymers. For four polymers, aggregation did not significantly change vertical velocities. However, PP particles showed a significantly slower settling velocity after aggregation: a decrease of 6.3 % based on mean averages, from 9.7 × 10−3 to 9.1 × 10−3 m·s−1. Theoretical calculations showed the amount of adsorbed sediment or biofilm required to induce a microplastic density change of ∼50 kg·m−3 was much higher than observed experimentally. Overall, this study indicates that the vertical velocities of larger microplastics are less influenced by interactions with natural particles than smaller microplastics.

Large polystyrene microplastics results in hepatic lipotoxicity in mice

Like small microplastics (MPs), recent studies reveal that large MPs could cause health risks in mice, even if they are not enriched in tissues. However, potential hepatoxicity following large MPs exposure and the underlying mechanisms have not been thoroughly investigated. In the present study, we explored the disruption of hepatic lipid metabolism and potential underlying toxic mechanisms in mice caused by long-term exposure to large polystyrene MPs (40–100 μm) based on a multi-omic approach. After 21 weeks of feeding foods containing MPs (50 and 500 mg/kg food), lipidomic revealed that environmentally relevant and higher doses MP exposures resulted in significant changes in a total of 20 lipid classes. Ceramide (Cer) and dihydroceramide (dhCer) were significantly reduced, while cholesteryl ester (CE), lysoalkylphosphatidylcholine (LPCO), lysophosphatidylethanolamine (LPE) and total glyceride (TG) were all elevated by MPs. The transcriptomic and other physiological data suggested that the potential toxic mechanisms may be related to disorders of fatty acid and cholesterol synthesis and metabolism disorders, and transporting of TG. Our findings demonstrate the hepatic lipotoxicity following exposure to environmentally relevant and higher doses of large MPs, calling for future research and management of the environmental risks of MPs with relatively large particle sizes.

Combined effects of salinity and polystyrene microplastics exposure on the Pacific oysters Crassostrea gigas: Oxidative stress and energy metabolism

Microplastics (MPs) pollution and salinity variation are two environmental stressors, but their combined effects on marine mollusks are rarely known. Oysters (Crassostrea gigas) were exposed to 1 × 104 particles L−1 spherical polystyrene MPs (PS-MPs) of different sizes (small polystyrene MPs (SPS-MPs): 6 μm, large polystyrene MPs (LPS-MPs): 50–60 μm) under three salinity levels (21, 26, and 31 psu) for 14 days. Results demonstrated that low salinity reduced PS-MPs uptake in oysters. Antagonistic interactions between PS-MPs and low salinity mainly occurred, and partial synergistic effects were mainly induced by SPS-MPs. SPS-MPs induced higher lipid peroxidation (LPO) levels than LPS-MPs. In digestive glands, low salinity decreased LPO levels and glycometabolism-related gene expression, which was related to salinity levels. Low salinity instead of MPs mainly affected metabolomics profiles of gills through energy metabolism and osmotic adjustment pathway. In conclusion, oysters can adapt to combined stressors through energy and antioxidative regulation.

Quantification and characterization of microplastics in the Thermaic Gulf, in the North Aegean Sea

The abundance and distribution of microplastics has largely increased during last years and the respective implications on the environment and human health is an emerging field in research. In addition, recent studies in the enclosed Mediterranean Sea in Spain and Italy have shown an extended occurrence of microplastics (MPs) in different sediments of environmental samples. This study is focused on the quantification and the characterization of MPs in the Thermaic Gulf in northern Greece. Briefly, samples from different environmental compartments such as seawater, local beaches and seven commercially available fish species collected and analyzed. MPs particles extracted and classified by size, shape, colour and polymer type. A total of 28,523 microplastic particles recorded in the surface water samples, with their numbers ranging from 189 to 7714 particles per sample. The mean concentration of MPs recorded on the surface water was 1.9 ± 2 items/m3 or 750,846 ± 838,029 items/km2. Beach sediment sample analysis revealed 14,790 microplastic particles, of which 1825 were large microplastics (LMPs, 1–5 mm) and 12,965 were small microplastics (SMPs, <1 mm). Furthermore, beach sediment samples showed a mean concentration of 733.6 ± 136.6 items/m2, with the concentration of LMPs being 90.5 ± 12.4 items/m2 and the concentration of SMPs being 643 ± 132 items/m2. Concerning fish deposition, microplastics were detected in intestines and mean concentrations per species ranged from 1.3 ± 0.6 to 15.0 ± 1.5 items/individual. The differences in microplastic concentrations between species were statistically significant (p < 0.05) and showed that mesopelagic fish contained the highest concentrations, followed by epipelagic species. The most common size fraction found in the data-set was 1.0–2.5 mm, and polyethylene and polypropylene were the most abundant polymer types recorded. This is the first detailed investigation of MPs in Thermaic Gulf, which raises concerns on their potential negative effects.

Spatial distribution of polystyrene nanoplastics and small microplastics in the Bohai Sea, China

Micro- and nano-plastic (MNP) pollution has attracted public concerns. Currently, most environmental researches focus on large microplastics (MPs), while small MNPs that have great impacts on marine ecosystems are rarely reported. Understanding the pollution levels and distribution patterns of small MNPs could help assess their potential impacts on the ecosystem. Polystyrene (PS) MNPs were often used as models to assess their toxicity, hence, we collected 21 sites in a Chinese sea area (the Bohai Sea) to analyze their pollution level and horizontal distribution in surface water samples, and vertical distributions in five sites with the water depth >25 m. Samples were filtered by glass membranes (1 μm) to trap MPs, which were frozen, ground, dried, and detected by pyrolysis-gas chromatography–mass spectrometry (pyGC-MS); while the nanoplastics (NPs) in the filtrate were captured with alkylated ferroferric oxide (Fe3O4) to form aggregates, which were separated by glass membrane (300 nm) filtration for pyGC-MS determination. Small PS MPs (1–100 μm) and NPs (<1 μm) were detected in 18 samples with the mass concentrations ranging from <0.015 to 0.41 μg/L, indicating that PS MNPs are widely present in Bohai Sea. Our study contributes to understanding the pollution levels and distribution patterns of MNPs (<100 μm) in the marine system and provides valuable data for their further risk assessment.

Comparative evaluation of the carbonyl index of microplastics around the Japan coast

The carbonyl index (CI) of polyethylene and polypropylene microplastics (MPs) (2950 particles) collected in coastal waters around Japan was investigated. The CI of MPs was calculated by the specified area under band technique. The mean MP CI in all samples (regardless of shape and color) was 0.69 ± 0.34 and 0.70 ± 0.34 for polyethylene and polypropylene, respectively, and there was no significant difference in the color or shape of the MPs. The polyethylene, white, and fragment MPs CI was negatively (p < 0.05) correlated with the major length of the MPs. Large MPs with relatively little deterioration were distributed along the west coast of the Sea of Japan, whereas small MPs were distributed along the east coast. Our findings of this gradual change in the deterioration of MPs, based on geographical distribution, are in accordance with literature CI–size and MP degradation hypotheses.

Species sensitivity distributions of micro- and nanoplastics in soil based on particle characteristics

Micro- and nanoplastics are released into the soil through various anthropogenic activities; however, research on ecological risk assessment (ERA) of soil microplastics is limited. In this study, the species sensitivity distributions (SSDs) of representative groups of soil biota were analyzed to determine their sensitivity to microplastic properties. A total of 411 datasets from apical endpoint data within 74 studies were classified and utilized in SSD estimation. The hazardous concentrations for 5% of species for microplastics was 88.18 (40.71–191.00) mg/kg soil. It has been established that small-sized microplastics are more toxic to soil organisms than larger microplastics. Most microplastics were spherical and polystyrene, exhibiting the most adverse effects among all the microplastic types assessed herein. The results suggest that physical characteristics of microplastics are important toxicity determinants in soil ecosystems. Given the potential for adverse environmental effects, further effective management strategies should urgently be employed in these areas. This study provided an integrated perspective of microplastic ecotoxicity in soil. In addition, SSDs were estimated using larger datasets and for more species than in previous studies. This is the first study to consider microplastic properties for estimating SSD.

Removal of pristine and aged microplastics from water by magnetic biochar: Adsorption and magnetization

Adsorption is an efficient and eco-friendly removal technique for small pristine microplastics in water. However, small pristine microplastics are not representative of those large microplastics in natural water with different aging levels. Whether the adsorption technique is effective in removing large aged microplastics from water remained unknown. To this end, the removal efficiency of large polyamide (PA) microplastics with different aging time by magnetic corncob biochar (MCCBC) was evaluated under different experimental conditions. After treated by heated-activated potassium persulfate, the physicochemical properties of PA have changed dramatically, as evidenced by rough surface, decreased particle size and crystallinity, and increased oxygen-containing functional groups, which enhanced with aging time. These changes promoted the combination of aged PA and MCCBC, thereby resulting in a higher removal efficiency of aged PA (~97 %) than that of pristine ones (~25 %). It is supposed that the adsorption process was a result of complexation, hydrophobic interaction, and electrostatic interaction. Increased ionic strength inhibited the removal of both pristine and aged PA, and neutral pH conditions favored PA removal. Furthermore, particle size played a great role in the removal of aged PA microplastics. When the particle size of aged PA was smaller than 75 μm, their removal efficiency was significantly increased (p < 0.01). The small PA microplastics were removed by adsorption, whereas the large ones were removed by magnetization. These research findings highlight magnetic biochar as promising technique for removing environmental microplastics.

Microplastics in a pelagic squid (Dosidicus gigas) from the Eastern tropical Pacific Ocean: Characteristics, spatial variation, and preliminary risk assessment

Despite concerns about the environmental impact of microplastics (MPs), knowledge of MP contamination levels in pelagic squid is lacking. This study investigated the stomach of an ecologically and commercially important but poorly known squid species, the jumbo squid Dosidicus gigas, found in the tropical and Southern temperate Pacific. We examined the characteristics and spatial distribution of MPs in fifty D. gigas (16.0–37.8 cm mantle length) and assessed potential MP pollution risks. MPs were detected in 50.0% of specimens and had an average abundance of 0.88 ± 1.12 items/individual and 0.24 ± 0.36 items/g stomach weight, and were sized 58.42–2,944.85 μm. The MPs were dominated by polyethylene terephthalate (31.82%) in polymer type, fragments (54.55%) and fibers (43.18%) in shape, and blue (59.59%) in color. All specimens could be evaluated as low risk. No statistically significant correlations were found between the MP abundances and D. gigas stomach weight, stomach fullness index, distance from the coast, and mantle length. While regression analyses showed that fuller stomachs contained larger MPs. Spatial variations in shape and polymer composition suggest that low-density fibrous MPs could be easily transported offshore by upwelling and/or ocean currents. These results indicate intraspecific variation in D. gigas MP contaminants and underscore the need to assess the potential site-specific ecotoxicological consequences of increased plastic pollution to pelagic squid.

Characterization of microplastic in trawl fish caught in Padang City (Indonesia) coastal area

Abstract. Edwin T, Primasari B, Purnama RA. 2023. Characterization of microplastic in trawl fish caught in Padang City (Indonesia) coastal area. Biodiversitas 24: 516-522. Marine organisms can ingest microplastics that are distributed in the oceans. It can harm marine organisms because carcinogenic materials easily attach to microplastics. Trawl fish is a commercial fish with a high demand from people in Padang City, West Sumatera, Indonesia. This study aimed to analyze the abundance of microplastics in the gastrointestinal tract of fish. Also, analyze the microplastic characteristics in trawl fish caught on Pasir Jambak Coast and Purus Coast in Padang City. The species studied were Sulphur goatfish (Upeneus sulphureus), Indian mackerel (Rastrelliger kanagurta), and White sardinella (Sardinella albella). Microplastics were identified using microscopy and FTIR spectroscopy. Microplastic abundance in Sulphur goatfish, Indian mackerel, and White sardinella was 3.89±1.36 per fish, 4.22±1.28 particles per fish, and 2.50±0.46 particles per fish, respectively. The size of the most commonly found microplastics ranged from 1-5 mm and was categorized as the Large Microplastic (LMP) type. Fourier Transform Infra-Red (FTIR) spectroscopy analysis showed that the origin of the type of microplastic polymer found was Polyethylene Terephthalate (PET). Statistically, it shows that the difference in the location and time of sampling does not provide a significant difference in the concentration of microplastics in fish and seawater. The results of this study indicated that microplastics were found in the waters and all fish samples on the coast of Padang City studied. Microplastics in the trawl fish can be used to manage plastic waste in the city to prevent a worse impact due to plastic pollution in the future.

Microplastics promoted cadmium accumulation in maize plants by improving active cadmium and amino acid synthesis

Combined pollution from microplastics (MPs) and cadmium (Cd) can influence soil environment and soil biota, altering plant growth and development, and Cd mobilization. We investigated the effects of polystyrene (PS) and polypropylene (PP) MPs alongside Cd on soil Cd bioavailability, rhizosphere soil metabolomics, bacterial community structure, and maize (Zea mays L.) growth in two soil types (red soil and cinnamon soil). Although the addition of PS/PP-Cd promoted Cd accumulation in maize plants overall, there were large-particle-size- and small-particle-size-dependent effects in the red soil and cinnamon soil, respectively. The difference is mainly due to the capacity of the large particle size MPs to significantly reduce soil pH, improve soil electrical conductivity (EC), promote active Cd, and intensify Cd mobilization in red soil. In contrast, small-size MPs in cinnamon soil promoted the synthesis and secretion of rhizosphere amino acids and soil metabolites, thus promoting Cd absorption by maize roots. Soil microorganisms also improved Cd bioavailability via C-related functional bacteria. Overall, our study provides novel insights on the potential effects of combined MPs and Cd pollution on soil ecology and agricultural production, enhancing our understanding of rhizosphere metabolites in different soils.

Influencing factors for microplastic intake in abundant deep-sea lanternfishes (Myctophidae)

Plastic debris is ubiquitous in the hydrosphere. Yet, we lack an understanding of contamination among deep-sea species and primarily how each trait can influence microplastic intake. We investigated microplastic contamination in the digestive tract of hyper-abundant mesopelagic lanternfishes (n = 364 individuals) from the Southwestern Tropical Atlantic, captured from 90 to 1000 m depth. Overall, microplastics were detected in most individuals analysed (frequency of occurrence = 68 %). Large microplastics, mostly of a filamentous shape were the most frequent, followed by smaller fragments and foams. Microplastics made of high-density polymers (PET, PVC, PA, SBR rubber) were more prevalent than low-density ones (PE, EVA and PBD rubber), especially under deeper layers. Larger microplastics were detected in lanternfishes captured off the northeastern Brazilian coast (mean 0.88 ± SE 0.06 mm) compared to those from around the Rocas Atoll and Fernando de Noronha Archipelago (0.70 ± 0.07 mm; p≤ 0.05), ∼350 km from the continent. Moreover, lanternfishes that migrate from the upper mesopelagic (200–500 m) to the epipelagic layers (<200 m) had simultaneously the highest intake and the smallest particles (1.65 ± 0.17 particles individual-1 and 0.55 ± 0.07 mm; p≤ 0.05). Biological mediated transport of microplastics from the epipelagic to the mesopelagic waters was evinced, but fishes foraging in shallower layers had the lowest intake (1.11 ± 0.10 part. ind.-1; p≤ 0.05). Furthermore, the jaw length was positively associated with an increment in microplastic intake (Incidence Rate Ratio = 1.1; p≤ 0.05). The lanternfishes that preferably prey upon fish larvae are more prone to microplastic intake than their counterparts, which forage mostly on crustaceans and gelatinous zooplankton (p≤ 0.05).

Effects of microplastics on the water characteristic curve of soils with different textures

Microplastic (MP) pollution in the soil severely damages the soil structure and affects the soil water-holding property, thereby affecting the soil water characteristic curve (SWCC). After polyethylene MP (PE-MP) addition at three concentrations (0.5%, 1%, and 2%) under three particle sizes (150 μm, 550 μm, and 950 μm) and two soil textures (sandy soil and loamy soil), SWCCs were measured and fitted with the van Genuchten model. The soil pore structure characteristics were obtained based on CT scanning combined with soil pore three-dimensional reconstruction to quantitatively analyze the relationships between MP properties and soil structure and the SWCC. Low concentrations (0.5%) of PE-MPs did not significantly affect the soil water content, while the accumulation of PE-MPs at a high concentration (2%) strongly affected the soil water-holding property, with small PE-MPs (150 μm) exerting significantly positive effects on the water-holding capacity of loamy soil and 950-μm MPs reducing the soil water content more strongly in sandy soil. The contributions of MP properties and soil textures to the SWCCs differed, and the impact of soil texture on the SWCCs was significantly higher than those of MP concentrations and particle sizes. Differences in MP occurrence characteristics and soil textures also led to variations in the fitted hydraulic parameters of the SWCCs. The addition of 2% 150-μm PE-MPs to loamy soil increased the soil porosity and surface area, while the addition of a higher concentration of large PE-MPs (2%, 950 μm) to sandy soil reduced soil porosity and circularity. This is related to the addition of a large number of small MPs, which may adsorb and bind many smaller soil particles to form larger, water-stable agglomerated structures, while the addition of high concentrations of large MPs in sandy soils may be related to the destruction of the original capillary pore structure of sandy soils and the weakening of soil capillarity. This study provides a theoretical basis for agroecological risk assessments.

Microplásticos em sedimentos depositados pelo do escoamento da água da chuva em um centro povoado nos Andes peruanos

ABSTRACT Microplastics (MPs) are present in surface sediments deposited on city streets as a result of stormwater runoff. The objective of this study was to determine the abundance and characteristics of MPs in surface sediments deposited by stormwater runoff from the village of Madeán in the Peruvian Andes based on size, shape, and color. Surface sediment samples were collected in triplicate at each of the eight sample sites. The sediments were deposited in some parts of the streets of this village due to the effect of rainwater runoff. The separation of MPs from the sediment was carried out in the laboratory by the density separation method with NaCl solution. The eight sampling sites in Madeán presented 292.91 ± 149.32 (MP Items/Kg of sediment) of MPs, showing significant differences in the abundance of MPs among the different sampling sites. The predominant characteristics of the MPs were small size (SMP) (50.95%) and large size MPs (LMP) (49.05%), being fiber (60.66%) and fragmented (38.39%) in morphology, and blue (29.86%), black (25.59%), and red (23.22%) in color, respectively. The following investigation suggests that solid waste is not being adequately managed by finding the presence of MPs in the sediments that are in the street ditches.

Assessment of pollution and risks associated with microplastics in the riverine sediments of the Western Ghats: a heritage site in southern India

There is very little knowledge on microplastic pollution in the Western Ghats (WG), a heritage site in southwest India. To address this, we have studied the spatiotemporal variations of sedimentary microplastics (MPs) from the River Sharavathi, a pristine river in the Western Ghats (WG), southern India. The rich biodiversity in the region makes it relevant to analyse the distribution of this emerging pollutant that is causing harm to the biota and the ecosystem. We analysed the sedimentological and carbon content (organic and inorganic) of these sediments and explored their relationship with MPs. Finally, risk assessment indices such as the Pollution Load Index (PLI), the Polymer Hazard Index (PHI), and the Potential Ecological Risk Index (PERI) were calculated to detect the levels of plastic pollution. The concentration of MPs ranged from 2.5 to 57.5 pieces/kg and 0 to 15 pieces/kg during the pre-monsoon and post-monsoon seasons, respectively. The dip in the MPs’ abundance during the post-monsoon season was due to the extremely high rainfall in the river basin during July–August 2019, which would have entrained the sedimentary MPs and transported them to the coast/Arabian Sea. Smaller MPs (0.3–1 mm) were more abundant than the larger MPs (1–5 mm), mainly due to the breakdown of sedimentary plastics by physical processes. Fragments, films, foams, and fibres were the main categories of MPs, and the main polymers were polyethylene, polyethylene terephthalate, and polypropylene. No significant relationship was observed between the sedimentological properties and microplastics, which may be due to the different physical properties of sediments and microplastics. The PLI, PHI, and PERI indices suggest different contamination levels in the river basin. Based on the PLI scores, all the samples belong to the hazardous level I suggesting minor risk category, and the risk of microplastic pollution falls under the high to hazardous risk category based on the PHI values. The PERI value ranged from 160 to 440 and 40 to 2240 during the pre-monsoon and post-monsoon seasons, respectively. The risk assessment in a region known for its rich biodiversity is crucial, as the data can be used by the district administration to mitigate plastic pollution.

Contamination of sea surface water offshore the Tokai region and Tokyo Bay in Japan by small microplastics.

A nested double neuston net was prepared and used to collect samples from the surface of coastal waters around Japan to obtain information about the properties of both small microplastics (SMPs; <350μm) and large microplastics (LMPs; >350μm). The SMP concentrations ranged from 1000 to 5900 pieces m-3 in the open ocean and averaged approximately 3000 pieces m-3 in the inner part of Tokyo Bay. The SMP concentrations were around 20-60 times greater than the LMP concentrations. By analyzing the seawater, we obtained a microplastic size distribution that spanned 50-5000μm. The LMPs mainly comprised packaging-related plastics, such as polyethylene (PE) and polypropylene, while the SMPs were dominated by paint-related plastics. SMPs derived from packaging materials (e.g., PE) may have gradually sank down from the sea surface when they were smaller than 600μm.

Assessing the size-dependent effects of microplastics on zebrafish larvae through fish lateral line system and gut damage.

This study evaluated the size-dependent effects of high-density polyethylene (HDPE) fragments in zebrafish. Larvae were exposed to HDPE microplastic (MP) in three sizes, small (14.12μm), medium (80.32μm), and large (120.97μm), at 20mg/L. Size-dependent effects in terms of MP intake, subsequent gut damage, and behavioral changes were observed. The results showed that HDPE exposure did not affect the survivability of zebrafish larvae but caused two significant changes. First, exposure to large MPs caused the most serious damage to hair cells and mechanosensory receptors in the fish's lateral line system. Second, exposure to MPs<100μm resulted in their ingestion by larvae, thereby causing morphological changes in the gastrointestinal tract. All larvae exposed to MPs showed behavioral pattern changes associated with size differences. This study improves our understanding of the effects of MPs on aquatic organisms and highlights the need to implement efficient strategies for plastic waste management.

Effect of Microplastics on the Germination and Growth of Terrestrial Plants

Objectives : The human beings of our globe are heavily reliant on the use of plastic products on a daily basis. Microplastics (MPs) are tiny particles that are formed as a result of plastic degradation. MPs can be found in terrestrial environment, but previous studies focused on the effects of MPs on marine environment and there are less studies on the effects of MPs on terrestrial environment. In particular, there is still a relatively limited number of studies on the effects of MPs on terrestrial plants. Therefore, this review paper aims to examine previous studies on the effect of MPs on the germination and growth of terrestrial plants.Methods : This review summarized the previous findings on the effect of MPs on the germination and growth of terrestrial plants in order to identify the research gaps and trends on the effects of MPs on terrestrial plants.Results and Discussion : Previous studies on the effect of MPs on the germination and growth of terrestrial plants were reviewed and the observations were summarized to find the gaps in this field of research. Previous studies showed that MPs can change soil properties and these changes can be different depending on the shape and size of MPs. MPs can also release chemicals such as phthalates and heavy metals that might have toxic effects on terrestrial plants. Different forms, types, and sizes of MPs were used in previous studies to study the effects on seed germination and growth of different plants. Most studies reported that MPs have negative effects on seed germination and plant growth (e.g., biomass, chlorophyll contents). Smaller MPs tend to have more significant effects than larger MPs. The changes in the soil properties due to MPs can change microbial community structures and this, in turn, may affect the soil-plant interaction.Conclusion : This study summarizes what have been reported in the previous studies on the effect of MPs on seed germination and growth of terrestrial plants. MPs are likely to affect seed germination and plant growth negatively, and this will eventually lead to reduction in food production and food quality. Owing to the various types, forms, and sizes of MPs that could be present in the terrestrial environment as well as the chemicals that could be released from MPs, there is much to explore to better understand the effect of MPs on terrestrial plants and the underlying mechanisms of such effects.